Numerous attempts have been made over the years to obtain a low fat spread with a taste, mouthfeel, structure, consistency, etc. that resembles butter as closely as possible. A number of features must be present in the final product in order to obtain this “butter feeling”:                spreadability at a temperature of about 5-25° C.,        easy to spread without spontaneous water release,        a creamy sensation devoid of both a gritty and a crystalline structure,        melting easily in the mouth,        devoid of a “sticky” sensation in the mouth        devoid of any unpleasant taste or off-taste,        preferably devoid of additives of non-dairy origin,        relatively easy and cheap to produce,        a “butter like” sensation according to a test panel        
Finally, the product should of course have a significantly lower fat content than butter.
A large number of technical problems must thus be solved in order to arrive at the desired product. Thus far, it has not been possible to produce a product that fulfils most or all of these criteria in a satisfactory manner. The large number of low fat spreads on the market, the growing concern for obesity and excessive caloric intake in general clearly indicates the need in the art for presenting the consumers with a satisfactory low fat spread product.
It has long been known in the art to stabilise the water phase of low fat spread emulsions in order to avoid phase separation and release of water during spreading. Well known stabilisers include hydro-colloids like starch, and carrageenan, and proteins like gelatine.
Most often, gelatine (in a concentration of about 3%) is used as a stabiliser of low fat spreads. An advantage of using gelatine is that a very low protein concentration is sufficient in order to achieve the desired consistency. Another advantage is that this approach is relatively cheap and the gelatine protein is almost flavour neutral. A disadvantage is that gelatine is of animal origin and some countries have therefore contemplated prohibiting the use of gelatine as a food ingredient due to the risks of e.g. BSE associated with such products, especially if the gelatine is derived from cattle bones. Vegetarians and health conscious consumers tend to prefer products devoid of gelatine.
It is also well known to stabilise the water phase of low fat spreads with proteins of dairy origin.
In SE-72116387 it is disclosed to use high contents (12-13% in the water phase) of Na-caseinate or Na-caseinate formed in situ from acidified and precipitated skimmed milk or buttermilk. A disadvantage of this approach is that production costs are increased with increasing protein contents. Also, high Na-caseinate contents result in a chalky mouthfeel and bitterness.
Several methods for producing whey protein “gels” are described. Whey protein gels known in the art have been used as a food ingredient for stabilisation of various product types such as in bakery and in meat products
In Int. Dairy Journal 6 (1996), 171-184 it is disclosed that the water phase of a low fat spread should contain about 20-25% native whey protein to reach a viscosity of 1.7 Pa s in order to create a stable water phase. The water phase can also be stabilised by a concentration of at least about 13% Na caseinate. However, when the final product comprises high protein contents (>8%), it tends to get an undesirable off taste or off flavour. Production costs are likewise increased with high protein contents. Therefore, low fat spreads stabilised with low concentrations of proteins of dairy origin need addition of additional stabilizers in order to arrive at an acceptable product.
Addition of various other additives such as stabilisers, thickeners, flavours, colours, etc. has thus far been considered mandatory in low fat spread production. Consequently, no low fat spreads stabilised with only small amounts of whey protein (<8%) are on the market.
Various disadvantages are, however, connected with addition of non-dairy additives. The identity of non-dairy additives must e.g. be listed on the declaration of contents and there is therefore a need in the art for low fat spreads that can be stabilised exclusively with e.g. proteins of dairy origin. In this respect it is worth noting that most consumers prefer natural products preferably without additives. There is furthermore a need in the art for finding a relatively cheap and simple method for producing such products.
There is also a need in the art for developing methods for cheap and efficient production of whey protein gels useful as a stabilising ingredient with a universal applicability within the food industry.
EP459566 A1 discloses a low fat spread comprising 10% fat and 13-14% calcium free denatured whey protein. A method involving shearing of the water phase is disclosed for producing a translucent thixotropic gel structure consisting of a viscous solution of particulate aggregates. A thixotropic gel in this document is understood as a gel that gradually recovers its viscosity when shearing of the gel is stopped. After the gel has been formed, mixing with fat phase is performed to obtain the low fat spread. The whey protein gel thus formed is a high concentration protein gel consisting of a web of mechanically broken protein strands.
U.S. Pat. No. 858,441 discloses a low fat spread comprising less than 35% fat, 0.05-0.5% commercially available heat denatured whey proteins as well as gelling agents (gelatine, starch, etc.) and (optionally) thickeners. A method is disclosed wherein the fat phase is heated to 60° C. The aqueous phase is then heated to 65° C. and slowly added to the fat phase. Another procedure is disclosed wherein oil and aqueous phase are mixed at 45° C.
EP 0076549 B1 discloses a low fat spread comprising 20-60% fat, 0.1-2% heat-denatured whey protein as well as a an appropriate amount of a thickening agent such as gelatine. A process for preparing the low fat spread is also disclosed, said process comprising first mixing a solution comprising whey proteins with fat under high pressure and subsequently subjecting this emulsion to heat treatment and pH adjustment to a pH of 3.5-6.
EP 1065938 B1 discloses a phase inverted oil-in-water low fat spread comprising 50-85% fat and 0.02-10% heat treated butter milk protein as well as additives such as emulsifiers and flavours. A method for producing a low fat spread comprising emulsifiers and involving super cooling of the fat phase is also disclosed. In this method, a fat phase comprising emulsifiers is mixed with a water phase comprising 2.2-2.5% buttermilk powder and the emulsion is subsequently heated to 75-80° C. In another embodiment, fat dairy cream is acidified to a pH of 5.2-5.3 using citric acid or a bacterial culture. This soured cream solution is then mixed with fat to reach the desired fat content and heated to a temperature of 75° C. before and/or after addition of additional fat.
Britten & Giroux Food Hydrocolloids 15 (2001) 609-617 discloses the effects of pH and calcium concentration on acid-induced gelation of whey proteins. The gels disclosed therein can be used as a stabilising food ingredient in dairy products of the o/w emulsion types, in particular yoghurt. A method is disclosed wherein an aqueous solution of 80 g whey protein/l with a calcium concentration of 0.6 mM is adjusted to a pH of 6.5; 7.5; and 8.5, respectively. The solution is heated at 90° C. for 15 minutes and subsequently cooled to 5° C. After cooling, pH is adjusted to 7.0 and without any further dilution, the solution is subjected to centrifugation at 20.000×g for 15 minutes in order to remove large insoluble protein aggregates, which were formed under all conditions assayed. Gel formation takes place immediately upon mixing with calcium rich yoghurt. The gel is mixed with yoghurt thereby thickening the yoghurt as well as increasing its protein content.
US2003/0091722 discloses whey protein products useful as a food ingredient. WPI (spray dried crude whey) from DAVISCO served as the protein source. Calcium is not removed from this product. In the product specification, DAVISCO states that the calcium content of the whey powder is about 0.1%, corresponding to about 0.004% or about 1.1.4 mM calcium in a 4% protein solution. A method is disclosed wherein a solution comprising 4% whey proteins is adjusted to a pH of about 8.0. This solution is heated to 75-95° C. in 10-120 minutes and thereafter cooled to room temperature. The heat treated solution is subsequently diluted to a protein concentration of about 1.5-3.5% protein and pH is adjusted to about 5.0-8.0 followed by a second heating step. It is disclosed that this two step heating process results in an immediate formation of a gel structure after the second heating step.